The touch technology, when applied to a smart terminal, enables a user to operate the terminal only by means of gesture operations. As such, a traditional mechanical keyboard is not needed, such that man-machine interaction is simpler and more direct.
At present, in most electronic products, a user's finger touch on the display screen would generate a two-dimensional coordinate input. However, with the development of touch technologies, for example, capacitive touch, pure finger touch may not accommodate the demands of multi-dimensional input of the user. Deploying the force detection technology (Force Touch) in the capacitive touch screen may increase an input dimension, which allows the touch screen to sense force information of the finger, and sense a light force or a heavy force. In this way, when the user's finger applies a force on the display screen, not only a two-dimensional coordinate input may be generated, but also a third-dimension force input may be generated, and different functions are input correspondingly, such that a better user experience is provided. For example, in the force detection technology of the touch screen, generally touch display is implemented in combination with a display device by means of detecting variations of a capacitor formed between a force sensing electrode and a reference electrode in a force sensor.
In the structure of a conventional capacitance detection manner, two capacitors are present. One capacitor is a force detecting capacitor, and the force detecting capacitor is formed between a force sensing electrode and a reference electrode, a gap which deforms when a force is applied is present between the force sensing electrode and the reference electrode, the capacitance of the force detecting capacitor represents the variation of the force. In addition to the force detecting capacitor, an additional load capacitor is also present. The load capacitor is formed between the force sensing electrode and a load electrode, and a gap between the force sensing electrode and the load electrode almost does not vary when a force is applied. Based on a conventional force detection model, since the load capacitor is present, in one aspect, the force detection model is complicated, and in another aspect, the total capacitance is increased. As a result, a variation amount of a detection voltage is lowered. In addition, impacts caused by environment changes to the load capacitor may be equivalently embodied on the force detecting capacitor. In the related art, the load capacitor is defaulted to be constantly unchanged in the force detection model, and thus the impacts which caused by the environment changes to the force performance is severe. Lastly, with the presence of the load capacitor, in the force detection model in the related art, environment self-calibration and self-calibration of an initial gap between the force sensing electrode and the reference electrode may not be implemented due to an externally connected capacitor.